Immunoassays using immobilized immunoreagents are in widespread use for the detection and quantification of biological molecules in samples. An immunoreagent, which may comprise an antibody or antigen, is first immobilized on a solid surface, such as a test tube, microplate, beads or the like. The immobilized reagent is then contacted with a sample solution containing a complementary immunoreagent, whereby an immobilized immunocomplex is formed between the immunoreagent and complementary immunoreagent. The immobilized immunocomplex can be separated from the unreacted sample solution, preferably with repeated washing of the immobilized immunocomplex. The separated immunocomplex may be subjected to further processing to quantitate the amount of the immunocomplex. Quantitative methods include, for example, radioimmunoassay (RIA), wherein the amount of the adsorbed immunocomplex may be determined by counting radioactive disintegrations; enzyme-linked immunosorbent assay (ELISA), wherein the adsorbed immunocomplex, which has an enzyme coupled thereto, is contacted with a substrate for the enzyme to produce a detectable product; immunofluorescent assay, wherein the fluorescent intensity of a fluorescent substance linked to the immunocomplex is measured; and chemiluminescent assay wherein the chemiluminescence of a chemiluminescent agent is measured.
Processes of the immunoassays, however, take time and resources. In addition, errors generated during the complex immunoassay accumulate gradually. For example, the enzymatic immunoassay is conducted by measuring the fluorescence intensity of the substrate after a certain period of time, either stopping the enzyme reaction with a stopping solution or not. In these steps, the duration from the initiation of enzyme reaction to the measurement should be strictly controlled, and so-called zero point correction is needed for the fluorescence intensity of the substrate because the intensity at the starting point is not always zero.
Except above descriptions, a researcher or an operator usually needs to load samples, pipette reagents or add a substrate into a test tube upon a bench, pour the liquid inside the test tube directly over the lab sink, and place the test tube into a machine, e.g. the ELISA reader, when the immunoassay has been initiated. Accordingly, it takes time and energy for the researcher or the operator to complete the assay. In addition, contaminations cannot effectively avoided as long as the assay is carried out by humans.